Friday, 24 February 2017

Experimental, Non-experimental, Descriptive, & Causal-comparative Research

Experimental research:

Experimental research

It is the research in which the researcher manipulates the independent variable and is interested in showing cause and effect.

The purpose of experimental research is to determine cause-and-effect relationships. The experimental research method enables us to identify causal relationships because it allows us to observe, under control conditions, the effects of systematically changing one or more variables.

Non-experimental research:

In non-experimental research, there is no manipulation of an independent variable. There is also no random assignment to groups by the researcher.

As a result of these two deficiencies (no manipulation and no random assignment), evidence gathered in support of cause-and-effect relationships in non-experimental research is severely limited and much weaker that evidence gathered in experimental research.

If the researcher wants to study cause and effect, he/she should try to conduct an experiment, but sometimes this is not feasible. When important causal research questions need to be answered and an experiment can’t be done, research must still be conducted. In research, we try to do the best we can.

For example, during the 1960s, extensive research linking cigarette smoking to lung cancer was conducted. Experimental research with humans was not possible because it would have been unethical. Therefore, in additional to experimental research with laboratory animals, medical researchers relied on non-experimental research methods for their extensive study of humans.

Descriptive Research:

Descriptive Research:

A descriptive study describes and interprets what is. It is concerned with conditions or relationships that exist, opinions that are held, processes that are going on, effects that are evident, or trends that are developing.

Descriptive study deals with the relationships between variables, the testing of hypotheses, and the development of generalizations, principles, or theories that have universal validity.
Descriptive study is sometimes divided into correlational research, causal-comparative research, and other descriptive research that is neither correlational nor designed to find out causation but describes existing conditions.

In carrying out a descriptive research project, in contrast to an experiment, the researcher does not manipulate the variable, decide who receives the treatment, or arrange for events to happen. Descriptive research also involves events that have already taken place and may be related to a present condition.

Descriptive research seeks to find answers to questions through the analysis of variable relationships. What factors seem to be associated with certain occurrences, outcomes, conditions, or types of behaviors?

Because it is often impracticable or unethical to arrange occurrences, an analysis of past events or of already existing conditions may be the only feasible way to study causation. This type of research is usually referred to as ex-post facto or causal-comparative research or, when correlational analyses are used, as correlational research.

Causal-comparative research:

In causal-comparative research, the researcher studies the relationship between one or more categorical independent variables and one or more quantitative dependent variables.

Because independent variable is categorical (that is males vs females, parents vs non-parents, or public school teachers vs private school teachers), the different group’s average scores on a dependent variable are compared to determine whether a relationship is present between the independent variable and dependent variable.

Despite the presence of the word causal included in the term causal-comparative research, one must keep in mind that causal-comparative research is a non-experimental research method, which means that there is no manipulation of an independent variable by a researcher.

Because of lack of manipulation and weaker techniques of controlling for extraneous variables, it is much more difficult to make statements about cause and effect in causal-comparative research than in experimental research.